The present invention relates to switching converter using several topologies. More particularly, the invention relates to a new control scheme to control the inductor current of the switching converter, and the switching converter can be used as a controllable current source for several applications.
In existed switching converter control schemes, there are several control methods. They can be classified as voltage mode control and current mode control. Due to the advantages of current mode control in switching converter, several current mode control schemes have been introduced and analyzed. For the current mode control, it can be classified as peak current mode and average current mode controls. So far, in order to simply implement, the peak current mode has been widely used in switching power supply application. In the peak current mode control scheme of the switching power supply, only part of the inductor current information is detected to adjust the equivalent current source. With the regulation of the voltage loop, the switching power supply can have a very proficient line and load performance. The average current mode is particularly useful in applications such as power factor correction and current source, e.g. battery charger and LED driver. In this kind of application, there is no a fast response voltage loop to adjust the output current due to a variable load. To implement the average current mode control, it is required to collect all information of the inductor current. In an online application, the requirement to collect all inductor current information is easier to satisfy. In an off line application, it will be much tougher due to an isolation requirement issue. The question from the application is whether there is a control scheme only to detect a part of the inductor current information to make the control performance much closer to the average current mode control performance. The present invention is to present a control scheme that can detect only a part of the inductor current and make the control performance much closer to the average current mode control performance; that is, a very proficient line and load regulation.